The name, Aften, is an acronym for:
A / Fifty-Two ENcoder
It is also Danish and Norwegian for 'evening'.

This program started as a simple cutting-out of the AC3 encoder from FFmpeg, but then I reworked the structure of the encoder a bit. Most of the basic code is still the same though. Here are some of the things I've changed so far.

I did a modification to add 6-WAV support. This can be useful because sometimes we want to change AC3 duration (for framerate conversions) and SoundStretch only support Mono WAVs, while BeSweet built-in SoundTouch doesn't work well in my experience. You can download sources and binary here:http://www.vmesquita.com/files/aften_6wav.zip

Good to see the Aften is having the correct AC3 channel order from the default wav-format order.
I believe the AC3 decoders are also responsible to restore the original wav-format channel order to play or transcode.
However :

Quote:

The Dolby Surround Mode flag is claimed by many users because, when is played by a hardware decoder, can switch automatically to DPL mode.

My h/w decoders(& probably many other decoders too) are auto/stereo/surround decoding mode manually selectable.
So as far as the mode is set to auto/surround, it decodes depending on the detected actual stream : AC3, DTS... | 5.1, 2.1,.., DPL II..
For an example, when I set the ac3 out mode in the FFDShow and change the mixer mode, it decodes all the 2.0 ch modes(DPL II, 2.0....) to DPL II mode(forced) automatically.

Probably only when the DD 2.0 contains the DPL mix, the ds meta info is used for some old decoders to be automatic to switch between DPL & STEREO mode.

__________________u know everything in the end, or now if aligned... no right(x).right(y) pls. it's confusing... : phase-shift /Jun.2006

Originally Posted by http://web.archive.org/web/20031206104650/http://dolby.com/pro/digaudio/pa.ma.1102.Standards.S.pdf on p17

On most equipment, the consumer can, through the product's user interface, choose the appropriate downmix for their playback system. Certain metadata parameters allow the engineer to select how the stereo downmix is constructed and which downmix is preferred, although the Lt/Rt downmix is usually the default.

The downmix modes(preferred/mixed) : Lt/Rt(Yes above : DPL), Lo/Ro(No : simple stereo). If we count the DPL II, I don't know how important this tag is any more.

But I agree, reserving & setting the correct options are not wasting the space and certainly useful for certain decoders or any other uses..

__________________u know everything in the end, or now if aligned... no right(x).right(y) pls. it's confusing... : phase-shift /Jun.2006

EDIT:
I have merged the 6 wav mod with the mods you posted, added the usage to when aften is called with no arguments, and fixed a little typo in your mod. Binary and source:http://www.mytempdir.com/794693

@vmesquita
Thanks for your job, but maybe there are a problem because your aften.exe never finish to encode. Stoped with Ctrl-C, the first part is ok and after a long silence. The parameters are taken ok.

@kurtnoise
Your new version works fine for me. Thanks for the patch.

In firsts tests I detected:
Aften accept any wav type, but only work with 16 bit Int wav's. With 24,32 bit Int or float the resultant ac3 is unusable. With 8 bit Int Aften abort.
Accept also WAVE_FORMAT_EXTENSIBLE (16 bit Int), then the faad output can be used directly with Aften.